The present invention relates to a data scanning and extracting apparatus for obtaining data by raster scanning a plurality of objects through observation regions called "windows" when images of the object are picked up by an image pickup device such as an ITV (industrial television) camera.
It is generally a well known practice in the art of image processing to provide observation regions or two-dimensional windows for observing an image picked up by an image pickup device such as a television camera and to take out only the image data which appears through the windows. This practice is especially advantageous in the case where useful information is limited to a particular location, since that location can be separated from other areas by a window, thereby facilitating data processing. Where items of useful information are scattered around in one displayed image, it is desirable to create as many windows as there are items of desired information and for the windows be available in different shapes. Typically, a window defining circuit and a data extraction circuit has been required for each window. Therefore, in order to generate a multiplicity of windows a complex and enormous circuit has been required to extract the data in each window.
One conventional window generator is arranged to create rectangular windows of desired sizes each having sides parallel to horizontal (X) and vertical (Y) directions of the television camera screen. FIG. 1 of the accompanying drawings is a block diagram of such a conventional window generator, and FIG. 2 is a diagram illustrative of the position and shape of a window to be generated.
In. FIG. 1, the window generator includes window boundary setting units (digital switches) 1 through 4, comparators 5 through 8, a vertical coordinate output counter 9, a horizontal coordinate output counter 10, and AND gates AN1 through AN3. Designated at VSYC is a vertical synchronous signal, HSYC a horizontal synchronous signal, WINDO a window (region) signal, and CKOM a clock signal for detecting horizontal positions. The setting units 1, 2 serve to set up vertical coordinates of the boundaries of a window to be generated, and the setting units 3, 4 serve to set up horizontal coordinates of the boundaries of a window. For example, in order to create a window W on a screen P, coordinates Y1, Y2, X1 and X2 are set up in the setting units 1, 2, 3 and 4, respectively. The comparators 5 through 8 are respectively supplied with the outputs from the setting units 1 through 4 and with output signals from the counters 9, 10 which are indicative of scanning positions on the image pickup device. The comparator 5, which is capable of detecting a starting boundary value, detects an interval in which a vertical scanning position exceeds a starting-boundary setting, and the comparator 6, which is capable of detecting a terminal boundary, detects an interval in which the vertical scanning position is short of a terminal boundary setting. The outputs from the comparators 5, 6 are ANDed by the AND gate AN1, which then produces a window signal indicative of the scan being within the vertical window range. Likewise, a window signal which indicates that the scan is within the horizontal window range is produced by the comparators 7, 8 and the AND gate AN2. These vertical and horizontal window signals are ANDed by the AND gate AN3, which produces a two-dimensional window signal WINDO.
The prior window generator however fails to form windows of shapes equivalent to rotated rectangular windows, that is, windows of shapes other than rectangles. Also, the number of comparators required increases with the number of windows to be formed, resulting in an enormous circuit arrangement if many windows are desired. A data processing circuit for such a plurality of windows needs to have parallel characteristic extracting circuits for the respective windows, because where a plurality of windows are to be produced horizontally, window signals are successively issued on a time-series basis for each horizontal scanning period to scan the windows from left to right, a condition which makes it impossible to process data in a window until after data in a preceding window has completely been processed.